They look like two-piece WWI US 'Great Seal' Buttons.
You have a couple of different varieties there, hopefully someone who knows US buttons better than I do will chime in.
Yeah got my coffee brewing. All the backs are blank. I just figure they are a poor boy type of uniform button. But for when? Thanks Antiquarian for the pic help. My grandma was going to try n ID these. I said "cool buttons!" Then she told me to take em cause she has so much else to deal with.
Yak1366 got the ID exactly right... US Army enlisted-ranks (meaning, Private through Sergeant) uniform buttons, showing a very-highly-raised shield on the spreadwinged eagle's chest, date from the Indian Wars era... more specifically, those are the version issued from 1875 to 1902, afterward replaced by the "Great Seal of the US" eagle-button for army uniforms.